Optimal prioritisation of watershed management measures for flood risk mitigation on a watershed scale

AbstractFlooding is an important global hazard that causes an average annual loss of over 40 billion USD and affects a population of over 250 million globally. The complex process of flooding depends on spatial and temporal factors such as weather patterns, topography, and geomorphology. In urban environments where the landscape is ever-changing, spatial factors such as ground cover, green spaces, and drainage systems have a significant impact. Understanding source areas that have a major impact on flooding is, therefore, crucial for strategic flood risk management (FRM). Although flood source area (FSA) identification is not a new concept, its application is only recently being applied in flood modelling research. Continuous improvements in the technology and methodology related to flood models have enabled this research to move beyond traditional methods, such that, in recent years, modelling projects have looked beyond affected areas and recognised the need to address flooding at its source, to study its influence on overall flood risk. These modelling approaches are emerging in the field of FRM and propose innovative methodologies for flood risk mitigation and design implementation; however, they are relatively under-examined. In this paper, we present a review of the modelling approaches currently used to identify FSAs, i.e. unit flood response (UFR) and adaptation-driven approaches (ADA). We highlight their potential for use in adaptive decision making and outline the key challenges for the adoption of such approaches in FRM practises.

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Assessment of renaturation measures for improvements in ecosystem services and flood risk mitigation

Journal of Environmental Management ◽

10.1016/j.jenvman.2021.112743 ◽

2021 ◽

Vol 292 ◽

pp. 112743

Author(s):

Elisabetta Strazzera ◽

Rossella Atzori ◽

Daniela Meleddu ◽

Vania Statzu

Keyword(s):

Ecosystem Services ◽

Flood Risk ◽

Risk Mitigation

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Needed: A systems approach to improve flood risk mitigation through private precautionary measures

Water Security ◽

10.1016/j.wasec.2020.100080 ◽

2020 ◽

Vol 11 ◽

pp. 100080

Author(s):

M.H. Barendrecht ◽

N. Sairam ◽

L. Cumiskey ◽

A.D. Metin ◽

F. Holz ◽

...

Keyword(s):

Flood Risk ◽

Systems Approach ◽

Risk Mitigation ◽

Precautionary Measures

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Variations of deep soil moisture under different vegetation types and influencing factors in a watershed of the Loess Plateau, China

Hydrology and Earth System Sciences ◽

10.5194/hess-20-3309-2016 ◽

2016 ◽

Vol 20 (8) ◽

pp. 3309-3323 ◽

Cited By ~ 35

Author(s):

Xuening Fang ◽

Wenwu Zhao ◽

Lixin Wang ◽

Qiang Feng ◽

Jingyi Ding ◽

...

Keyword(s):

Soil Moisture ◽

Influencing Factors ◽

Loess Plateau ◽

Vegetation Restoration ◽

Native Vegetation ◽

Watershed Scale ◽

Vegetation Types ◽

Deep Soil ◽

Soil Layers ◽

Management Measures

Abstract. Soil moisture in deep soil layers is a relatively stable water resource for vegetation growth in the semi-arid Loess Plateau of China. Characterizing the variations in deep soil moisture and its influencing factors at a moderate watershed scale is important to ensure the sustainability of vegetation restoration efforts. In this study, we focus on analyzing the variations and factors that influence the deep soil moisture (DSM) in 80–500 cm soil layers based on a soil moisture survey of the Ansai watershed in Yan'an in Shanxi Province. Our results can be divided into four main findings. (1) At the watershed scale, higher variations in the DSM occurred at 120–140 and 480–500 cm in the vertical direction. At the comparable depths, the variation in the DSM under native vegetation was much lower than that in human-managed vegetation and introduced vegetation. (2) The DSM in native vegetation and human-managed vegetation was significantly higher than that in introduced vegetation, and different degrees of soil desiccation occurred under all the introduced vegetation types. Caragana korshinskii and black locust caused the most serious desiccation. (3) Taking the DSM conditions of native vegetation as a reference, the DSM in this watershed could be divided into three layers: (i) a rainfall transpiration layer (80–220 cm); (ii) a transition layer (220–400 cm); and (iii) a stable layer (400–500 cm). (4) The factors influencing DSM at the watershed scale varied with vegetation types. The main local controls of the DSM variations were the soil particle composition and mean annual rainfall; human agricultural management measures can alter the soil bulk density, which contributes to higher DSM in farmland and apple orchards. The plant growth conditions, planting density, and litter water holding capacity of introduced vegetation showed significant relationships with the DSM. The results of this study are of practical significance for vegetation restoration strategies, especially for the choice of vegetation types, planting zones, and proper human management measures.

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Spatial Management Measures Alter Vessel Behavior in the Aleutian Archipelago

Frontiers in Marine Science ◽

10.3389/fmars.2020.579905 ◽

2021 ◽

Vol 7 ◽

Author(s):

Benjamin K. Sullender ◽

Kelly Kapsar ◽

Aaron Poe ◽

Martin Robards

Keyword(s):

North Pacific ◽

Risk Mitigation ◽

Spatial Scales ◽

Great Circle ◽

Ecological Impacts ◽

Study Region ◽

The North ◽

Management Measures ◽

Before And After ◽

The North Pacific

The Aleutian Archipelago and surrounding waters have enormous ecological, cultural, and commercial significance. As one of the shortest routes between North American and Asian ports, the North Pacific Great Circle Route, which crosses through the Aleutian Archipelago, is traveled by thousands of large cargo ships and tanker vessels every year. To reduce maritime risks and enhance navigational safety, the International Maritime Organization built upon earlier offshore routing efforts by designating five Areas To Be Avoided (ATBAs) in the Aleutian Islands in 2016. The ATBAs are designed to keep large vessels at least 50 nautical miles (93 km) from shore unless calling at a local port or transiting an authorized pass between islands. However, very few studies have examined the effectiveness of ATBAs as a mechanism for changing vessel behavior and thereby reducing the ecological impacts of maritime commerce. In this study, we use 4 years of satellite-based vessel tracking data to assess the effectiveness of the Aleutian ATBAs since their implementation in 2016. We determined whether vessels transiting the North Pacific Great Circle Route changed behavior after ATBA implementation, both in terms of overall route selection and in terms of compliance with each ATBA boundary. We found a total of 2,252 unique tankers and cargo vessels >400 gross tons transited the study region, completing a total of 8,794 voyages. To quantify routing changes of individual vessels, we analyzed the 767 vessels that transited the study region both before and after implementation. The percentage of voyages transiting through the boundaries of what would become ATBAs decreased from 76.3% in 2014–2015 (prior to ATBA designation) to 11.8% in 2016–2017 (after implementation). All five Aleutian ATBAs had significant increases in compliance, with the West ATBA showing the most dramatic increase, from 32.1% to 95.0%. We discuss the framework for ATBA enforcement and highlight the value of local institutional capacity for real-time monitoring. Overall, our results indicate that ATBAs represent a viable strategy for risk mitigation in sensitive ecological areas and that through monitoring, spatial protections influence vessel route decisions on multiple spatial scales.

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Novel use of climate model data for deriving future flood risk underwriting and risk selection data – A Hong Kong Case Study

10.5194/egusphere-egu21-15778 ◽

2021 ◽

Author(s):

Rebecca Alexandre ◽

Iain Willis

Keyword(s):

Climate Change ◽

Hong Kong ◽

Flood Risk ◽

Climate Model ◽

Risk Mitigation ◽

Flood Damage ◽

Flood Frequency ◽

Commercial Building ◽

Model Data ◽

Change Factors

The re/insurance, banking and mortgage sectors play an essential role in facilitating economic stability. As climate change-related financial risks increase, there has long been a need for tools that contribute to the global industry&#8217;s current and future flood risk resiliency. Recognising this gap, JBA Risk Management has pioneered use of climate model data for rapidly deriving future flood risk metrics to support risk-reflective pricing strategies and mortgage analysis for Hong Kong.JBA&#8217;s established method uses daily temporal resolution precipitation and surface air temperature Regional Climate Model (RCM) data from the Earth System Grid Federation&#8217;s CORDEX experiment. Historical and future period RCM data were processed for Representative Concentration Pathways (RCPs) 2.6 and 8.6, and time horizons 2046-2050 and 2070-2080 and used to develop fluvial and pluvial hydrological model change factors for Hong Kong. These change factors were applied to baseline fluvial and pluvial flood depths and extents, extracted from JBA&#8217;s high resolution 30m Hong Kong Flood Map. From these, potential changes in flood event frequency and severity for each RCP and time horizon combination were estimated.The unique flood frequency and severity profiles for each flood type were then analysed with customised vulnerability functions, linking water depth to expected damage over time for residential and commercial building risks. This resulted in quantitative fluvial and pluvial flood risk metrics for Hong Kong.Newly released, Hong Kong Climate Change Pricing Data is already in use by financial institutions. When combined with property total sum insured data, this dataset provides the annualised cost of flood damage for a range of future climate scenarios. For the first time, our industry has a tool to quantify baseline and future flood risk and set risk-reflective pricing for Hong Kong portfolios.JBA&#8217;s method is adaptable for global use and underwriting tools are already available for the UK and Australia with the aim of improving future financial flood risk mitigation and management. This presentation will outline the method, provide a comparison of baseline and climate change flood impacts for Hong Kong and discuss the wider implications for our scientific and financial industries.

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Conceptualization of a Critical Infrastructure Network – Model for Flood Risk Assessments

10.5194/egusphere-egu21-922 ◽

2021 ◽

Author(s):

Roman Schotten ◽

Daniel Bachmann

Keyword(s):

Risk Analysis ◽

Flood Risk ◽

Critical Infrastructure ◽

Risk Mitigation ◽

Mitigation Measures ◽

Critical Infrastructures ◽

Flood Exposure ◽

Infrastructure Network ◽

Flood Risk Analysis ◽

De Bruijn

In flood risk analysis it is a key principle to predetermine consequences of flooding to assets, people and infrastructures. Damages to critical infrastructures are not restricted to the flooded area. The effects of directly affected objects cascades to other infrastructures, which are not directly affected by a flood. Modelling critical infrastructure networks is one possible answer to the question &#8216;how to include indirect and direct impacts to critical infrastructures?&#8217;.Critical infrastructures are connected in very complex networks. The modelling of those networks has been a basis for different purposes (Ouyang, 2014). Thus, it is a challenge to determine the right method to model a critical infrastructure network. For this example, a network-based and topology-based method will be applied (Pant et al., 2018). The basic model elements are points, connectors and polygons which are utilized to resemble the critical infrastructure network characteristics.The objective of this model is to complement the state-of-the-art flood risk analysis with a quantitative analysis of critical infrastructure damages and disruptions for people and infrastructures. These results deliver an extended basis to differentiate the flood risk assessment and to derive measures for flood risk mitigation strategies. From a technical point of view, a critical infrastructure damage analysis will be integrated into the tool ProMaIDes (Bachmann, 2020), a free software for a risk-based evaluation of flood risk mitigation measures.The data on critical infrastructure cascades and their potential linkages is scars but necessary for an actionable modelling. The CIrcle method from Deltares delivers a method for a workshop that has proven to deliver applicable datasets for identifying and connecting infrastructures on basis of cascading effects (de Bruijn et al., 2019). The data gained from CIrcle workshops will be one compound for the critical infrastructure network model.Acknowledgment: This work is part of the BMBF-IKARIM funded project PARADes (Participatory assessment of flood related disaster prevention and development of an adapted coping system in Ghana).Bachmann, D. (2020). ProMaIDeS - Knowledge Base. https://promaides.myjetbrains.comde Bruijn, K. M., Maran, C., Zygnerski, M., Jurado, J., Burzel, A., Jeuken, C., & Obeysekera, J. (2019). Flood resilience of critical infrastructure: Approach and method applied to Fort Lauderdale, Florida. Water (Switzerland), 11(3). https://doi.org/10.3390/w11030517Ouyang, M. (2014). Review on modeling and simulation of interdependent critical infrastructure systems. Reliability Engineering and System Safety, 121, 43&#8211;60. https://doi.org/10.1016/j.ress.2013.06.040Pant, R., Thacker, S., Hall, J. W., Alderson, D., & Barr, S. (2018). Critical infrastructure impact assessment due to flood exposure. Journal of Flood Risk Management, 11(1), 22&#8211;33. https://doi.org/10.1111/jfr3.12288

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Agent‐based Modeling to Evaluate Human–Environment Interactions in Community Flood Risk Mitigation

Risk Analysis ◽

10.1111/risa.13854 ◽

2021 ◽

Author(s):

Yu Han ◽

Liang Mao ◽

Xuqi Chen ◽

Wei Zhai ◽

Zhong‐Ren Peng ◽

...

Keyword(s):

Flood Risk ◽

Risk Mitigation ◽

Agent Based Modeling ◽

Human Environment ◽

Agent Based

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Hydrodynamics of pedestrians' instability in floodwaters

Hydrology and Earth System Sciences ◽

10.5194/hess-21-515-2017 ◽

2017 ◽

Vol 21 (1) ◽

pp. 515-531 ◽

Cited By ~ 25

Author(s):

Chiara Arrighi ◽

Hocine Oumeraci ◽

Fabio Castelli

Keyword(s):

Experimental Data ◽

Froude Number ◽

Flood Risk ◽

Risk Mitigation ◽

Three Dimensional ◽

Numerical Results ◽

Mitigation Measures ◽

Dimensionless Numbers ◽

Large Variability ◽

Mobility Parameter

Abstract. People's safety is the first objective to be fulfilled by flood risk mitigation measures, and according to existing reports on the causes of casualties, most of the fatalities are due to inappropriate behaviour such as walking or driving in floodwaters. Currently available experimental data on people instability in floodwaters suffer from a large dispersion primarily depending on the large variability of the physical characteristics of the subjects. This paper introduces a dimensionless mobility parameter θP for people partly immersed in flood flows, which accounts for both flood and subject characteristics. The parameter θP is capable of identifying a unique threshold of instability depending on a Froude number, thus reducing the scatter of existing experimental data. Moreover, a three-dimensional (3-D) numerical model describing the detailed geometry of a human body and reproducing a selection of critical pairs of water depth and velocity is presented. The numerical results in terms of hydrodynamic forces and force coefficients are analysed and discussed. Both the mobility parameter θP and the numerical results hint at the crucial role of the Froude number and relative submergence as the most relevant dimensionless numbers to interpret the loss of stability. Finally, the mobility parameter θP is compared with an analogous dimensionless parameter for vehicles' instability in floodwaters, providing a new contribution to support flood risk management and educating people.

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